学步园

看了下，AndEngine里面Example中的PathModifierExample 的例子。大致了解到其实现的过程为：

指定元素要运行的路线，然后构造PathModifier，通过PathModifier动画来实现元素按指定路线行进。

public class PathModifierExample extends SimpleBaseGameActivity {
	// ===========================================================
	// Constants
	// ===========================================================

	private static final int CAMERA_WIDTH = 720;
	private static final int CAMERA_HEIGHT = 480;

	// ===========================================================
	// Fields
	// ===========================================================

	private RepeatingSpriteBackground mGrassBackground;

	private BitmapTextureAtlas mBitmapTextureAtlas;
	private TiledTextureRegion mPlayerTextureRegion;

	// ===========================================================
	// Constructors
	// ===========================================================

	// ===========================================================
	// Getter & Setter
	// ===========================================================

	// ===========================================================
	// Methods for/from SuperClass/Interfaces
	// ===========================================================

	@Override
	public EngineOptions onCreateEngineOptions() {
		Toast.makeText(this, "You move my sprite right round, right round...",
				Toast.LENGTH_LONG).show();

		final Camera camera = new Camera(0, 0, CAMERA_WIDTH, CAMERA_HEIGHT);

		return new EngineOptions(true, ScreenOrientation.LANDSCAPE_FIXED,
				new RatioResolutionPolicy(CAMERA_WIDTH, CAMERA_HEIGHT), camera);
	}

	@Override
	public void onCreateResources() {
		BitmapTextureAtlasTextureRegionFactory.setAssetBasePath("gfx/");
		// 实例化可重复的精灵背景
		this.mGrassBackground = new RepeatingSpriteBackground(CAMERA_WIDTH,
				CAMERA_HEIGHT, this.getTextureManager(),
				AssetBitmapTextureAtlasSource.create(this.getAssets(),
						"gfx/background_grass.png"),
				this.getVertexBufferObjectManager());
		// 创建纹理集
		this.mBitmapTextureAtlas = new BitmapTextureAtlas(
				this.getTextureManager(), 128, 128);
		// 创建纹理区域
		this.mPlayerTextureRegion = BitmapTextureAtlasTextureRegionFactory
				.createTiledFromAsset(this.mBitmapTextureAtlas, this,
						"player.png", 0, 0, 3, 4);
		this.mBitmapTextureAtlas.load();
	}

	@Override
	public Scene onCreateScene() {
		this.mEngine.registerUpdateHandler(new FPSLogger());

		final Scene scene = new Scene();
		scene.setBackground(this.mGrassBackground);

		/* Create the face and add it to the scene. */
		final AnimatedSprite player = new AnimatedSprite(10, 10, 48, 64,
				this.mPlayerTextureRegion, this.getVertexBufferObjectManager());
		// 指定其行走的路线
		final Path path = new Path(5).to(10, 10).to(10, CAMERA_HEIGHT - 74)
				.to(CAMERA_WIDTH - 58, CAMERA_HEIGHT - 74)
				.to(CAMERA_WIDTH - 58, 10).to(10, 10);

		/* Add the proper animation when a waypoint of the path is passed. */
		player.registerEntityModifier(
		// 循环实体修饰集合
		new LoopEntityModifier(
		// 构造路线修饰实体
				new PathModifier(30, path, null, new IPathModifierListener() {
					@Override
					public void onPathStarted(final PathModifier pPathModifier,
							final IEntity pEntity) {
						Debug.d("onPathStarted");
					}

					@Override
					public void onPathWaypointStarted(
							final PathModifier pPathModifier,
							final IEntity pEntity, final int pWaypointIndex) {
						Debug.d("onPathWaypointStarted:  " + pWaypointIndex);
						switch (pWaypointIndex) {
						// 人物向下走的时候，使用第6到第8张图
						case 0:
							player.animate(new long[] { 200, 200, 200 }, 6, 8,
									true);
							break;
						// 人物像向走的时候，使用第3到第5张图
						case 1:
							player.animate(new long[] { 200, 200, 200 }, 3, 5,
									true);
							break;
						// 人物向上走的时候，使用第0到2张图
						case 2:
							player.animate(new long[] { 200, 200, 200 }, 0, 2,
									true);
							break;
						// 人物向左走的号死后，使用第9到11张图
						case 3:
							player.animate(new long[] { 200, 200, 200 }, 9, 11,
									true);
							break;
						}
					}

					@Override
					public void onPathWaypointFinished(
							final PathModifier pPathModifier,
							final IEntity pEntity, final int pWaypointIndex) {
						Debug.d("onPathWaypointFinished: " + pWaypointIndex);
					}

					@Override
					public void onPathFinished(
							final PathModifier pPathModifier,
							final IEntity pEntity) {
						Debug.d("onPathFinished");
					}
				}, EaseSineInOut.getInstance())));
		scene.attachChild(player);

		return scene;
	}

	// ===========================================================
	// Methods
	// ===========================================================

	// ===========================================================
	// Inner and Anonymous Classes
	// ===========================================================
}